The present invention concerns a method for managing the kinematics of a seat having at least three seat elements able to move with respect to each other and at least two actuators for moving the three elements with respect to each other.
This method applies notably to vehicle seats able to be used notably in aircraft for transporting passengers.
These seats generally have a squab which can be moved with respect to the base. An inclinable back rest is articulated at one end of the squab, whilst at its other end there is articulated a leg rest extended by a movable foot rest.
Electrical actuators equip the seat, in order to move the different elements thereof with respect to each other.
In some seats, the height of the squab can be modified by virtue of the movement possible between the squab and the base of the seat. The movement can be effected by means of a specific actuator located between the squab and the base. It can also result from the mechanical structure of the seat which mechanically connects the squab to another element of the seat, and for example its back rest. Thus, for example, when the seat back rest is moved to its upright position, the squab is simultaneously lowered.
In a seat equipped with such synchronism between the movements of the back rest and squab, it will be understood that, when the leg rest is essentially vertical and the foot rest is sufficiently brought out, the lowering of the squab during the movement of the back rest can cause the bottom end of the foot rest to come into contact notably with the floor, the foot rest/leg rest assembly being supported solely by the end of the squab. When the squab is lowered, the foot rest/leg rest assembly is then subjected to high mechanical stresses which may damage it.
Generally it will be understood that the effect of the movement of a seat element under the control of an actuator may cause damage to other elements of the seat when the latter comes into contact with an obstacle.
The aim of the invention is to afford a solution to this problem by proposing a method of managing the kinematics of the seat preventing an element of the seat driven by another element of the seat from undergoing excessive mechanical stresses, when an actuator acting indirectly on it is actuated.
To this end, the object of the invention is a method of managing the kinematics of a seat of the aforementioned type, characterised in that, when a first actuator is actuated in at least one direction, it includes a step of actuating a second actuator first of all in one given direction and then in the opposite direction.
According to particular embodiments, the method includes one or more of the following characteristics:
the actuation of the second actuator in the given direction is effected for a first predetermined duration;
the actuation of the second actuator in the opposite direction is effected for a second predetermined duration;
the first and second predetermined durations are such that, according to the speed of movement of the second actuator in the given direction and in the opposite direction, the movement travels in the two directions are substantially identical;
before the step of actuating the second actuator in the said given direction, it includes a step of measuring and storing the current position of the second actuator, and the actuation of the second actuator in the said opposite direction is effected at most until the second actuator returns to the said stored position;
it includes a step of monitoring at least one variable characteristic of the force produced by the second actuator, during its use in the said opposite direction, and a step of estimating at least one predetermined evaluation criterion relating to the characteristic variable or variables, and it includes a step of actuating the second actuator according to a predefined actuation instruction, putting an end to its movement in the said opposite direction, when at least one of the predetermined evaluation criteria is satisfied;
the said predetermined actuation instruction is an instruction chosen from the group consisting of the stoppage of the second actuator and the driving of the second actuator in the said given direction; and
at least one variable characteristic of the force produced is a variable characteristic of the electric current consumed by the second actuator chosen from the group consisting of the intensity consumed by the actuator and a derivative with respect to the time of the intensity consumed by the actuator.
Another object of the invention is a seat including at least at least three seat elements movable with respect to each other and at least two actuators for the movement of the three elements with respect to each other, characterised in that it has means of actuating a first actuator in one direction and automatic means of actuating a second actuator first of all in a given direction and then in the opposite direction, when the first actuator is actuated in at least one direction.
According to particular embodiments, the seat has one or more of the following characteristics:
it has:
a movable squab;
a back rest articulated on the squab;
a leg rest articulated on the squab; and
a foot rest mounted so as to be able to move with respect to the leg rest; and
the first actuator is adapted for the conjoint movement of the back rest and squab whilst providing the lowering of the seat when the back rest is moved upright; and
the second actuator is adapted for the movement of the foot rest with respect to the leg rest; and
it has:
a movable squab;
a back rest articulated on the squab; and
a leg rest articulated on the squab; and
the first actuator is adapted for the conjoint movement of the back rest and squab whilst providing the lowering of the squab when the back rest is moved upright; and
the second actuator is adapted for the movement of the leg rest with respect to the squab.